My understanding is that Brown tends to be better known for its applied math rather than its pure math (but of course, the Brown faculty member can advise best on this).
It might be worth looking at course catalogs for the schools of interest to make sure they offer the courses you want.
Here is Brown’s course listing for this semester. I recommend that you also review other semesters from the drop-down box on the left, as offerings change each semester and sometimes each year.
Make sure to look at both the MATH offerings and the APMA (applied math) offerings, as well as perhaps some math-related disciplines: ECON, CSCI, DATA and perhaps ENGN.
Good luck – I think you are a strong candidate, but as always, these are high reach schools for everyone.